I had an email asking about entry holes for hollowing yesterday. I’ve replied, but thought I’d post an answer here for anybody else who wondered about it.
The vessel turned by my student had a 40mm entry hole. This seems a happy compromise size, allowing relative ease of access for tools, reducing stress for the student, and saving the nasty catches which lead to hollow fire wood.
There aren’t any “rules” as such for entry hole size. You should make the entry a size which suits you. If you are happy working in a restricted entry, then do so. If not, widen the entry hole. Simple really. No matter where you decide to start, you will get to the point where you fancy a challenge and decide to go smaller, but this is always limited by your particular hollowing tool.
The only real concerns are of safety and success. If you make it so small you are almost bound (by lack of experience, for instance) to have a catch and shatter the piece, then you risk a sharp thin piece of wood coming at you at a rate of nots. Not a good feeling! And if you make it so small that the effort and concentration put you off ever trying hollowing again, then it is equally pointless. Hollowing can be fun and confidence building. It can also be tedious! All the shavings to remove…stop clear start, stop clear start…
And this is actually where most people fail…they cut and cut and cut and the shavings build up in the vessel, pressed tightly into the widest part of the vessel by centrifugal force…the tool hits this mass of compressed wood and BANG! So the message is to stop the lathe (always!) and clear the shavings on a tediously regular basis. In fact, if the tool is cutting well, this is perhaps after every third cut.
Here’s a picture of the example I had turned for my student with the entry hole diameter indicated by a rule…
happy hollowing…
